1. Field of the Invention
This invention relates, in general, to computer system cooling, and in particular, to proactive cooling of computer chips.
2. Description of the Related Art
During normal operation, microelectronic chips generate heat. This heat is typically removed via a cooling system, enlisting various methods including metal heat sinks, fans, and mechanical refrigeration. As microelectronic chips execute tasks with varying levels of workload, the chips create commensurate changes in heat. To avoid under or over cooling, current cooling systems rely on temperature measurements that lag the change in power as feedback in order to regulate cooling. For example, a chip experiences an increase in workload. This workload increase creates an increase in power consumption. This increase in power consumption results in a temperature increase to the chip. The cooling system detects this temperature change and reacts by increasing cooling. The increased cooling returns the microelectronic chip back to its original temperature. In addition, on chip control techniques have been developed to regulate chip temperatures by regulating voltage, as described in On-Chip Control of Thermal Cycling, U.S. patent Ser. No. 13/040,094, which is hereby incorporated by reference.
Unfortunately, as the cooling system is reacting to the temperature, the microelectronic chip experiences an increase and then decrease in temperature. Even in the best systems, this thermal cycling is a significant result of the heat-temperature-feedback control. As microelectronic chip technology advances, the temperature extremes, as well as cycling rates, of this cycling will increase. The problem arises in that this cycling reduces package and silicon reliability and forces designers to build in temperature buffer that can reduce microelectronic chip performance. Also, this cycling can degrade cooling system effectiveness and significantly reduce cooling lifetime.